Synthesis of pyrazolinylnaphthalic acid derivatives

ABSTRACT

The invention pertains to a method for preparing derivatives of the pyrazolinylnaphthalic acid having the general formula  
                 
 
     where Ar 1  and Ar 2  are unsubstituted or substituted phenyl radicals bearing in the para position an alkylated or acylated oxy- or amino group, or a polynuclear aryl radical, and Ar 3  is a substituted N-naphthalimid or 1,8-naphthylene-1′,2′-benzimidazole. Compounds ofthe above general formula are high-efficient red organic luminophors and are used widely as luminescent components of dyes for plastics and liquid scintillators, in hydrogeology to study water streams, to label the chemical industry wastewaters, as laser dyes, etc.

CROSS REFERENCE TO RELATED PATENT APPLICATIONS

[0001] This application is related to and claims priority on Ukrainian patent application serial number 99127167, filed Dec. 28, 1999.

FIELD OF THE INVENTION

[0002] The invention relates to a method for preparing derivatives of the pyrazolinylnaphthalic acid having the general formula

[0003] where

[0004] Ar₁ and Ar₂ are unsubstituted or substituted phenyl radicals bearing in the para position an alkylated or acylated oxy- or amino group, or a polynuclear aryl radical; and

[0005] Ar₃ is a substituted N-naphthalimid or 1,8-naphthylene-1′,2′-benzimidazole.

BACKGROUND OF THE INVENTION

[0006] A method is known (see Ref. 1-USSR Author's Certificate No. 179,324, Cl. C09d) for preparing derivatives of pyrazolinylnaphthalic acid having the general formula

[0007] where

[0008] R₁ is a unsubstituted or substituted aromatic or heterocyclic radical;

[0009] R₂ is a unsubstituted or substituted aromatic radical;

[0010] R₃ is an alkyl, aryl, alkoxy, or halogen.

[0011] Compounds ofthis general formula are organic luminophors with emission in the orange-red and red range of the visible spectrum.

[0012] The above-mentioned compounds are prepared proceeding from condensation products of 4-acetylnaphthalic anhydride with unsubstituted or substituted o-phenylene diamine in glacial acetic acid. The yellowish green crystals formed are filtered off and recrystallized from acetic acid. The acetyl derivative of 1,8-naphthylene-1′,2′-benzimidazole obtained is treated with aromatic or heterocyclic aldehyde in ethanol in the presence of sodium hydroxide, stirred at ambient temperature, and diluted with water. The precipitate formed is separated by filtration and recrystallized from acetic acid. An unsaturated ketone is obtained. The ketone is treated with phenyl hydrazine or its substitute in glacial acetic acid under reflux, the crystals precipitated from the cooled solution are filtered off, washed with methanol, and dried. The product is obtained as water-insoluble red or dark-red crystals soluble in conventional organic solvents. The ready (commercial grade) product yield is from 62 to 85%. Luminescence characteristics: in toluene, λ_(max)=598 to 610 nm; in crystal form, λ_(max)=620 to 670 nm.

[0013] Another method has been also described (see Ref.2-USSR Author's CertificateNo. 196,873, Cl. C09d) for preparing derivatives of pyrazolinylnaphthalic acid having general formula

[0014] where

[0015] R₁ and R₂ are unsubstituted or substituted aromatic radicals. Compounds of this structure are organic luminophors with orange, orange-red, and red emission.

[0016] The method consists of a first synthesis stage, in which a mixture of 4-acetylnaphthalic anhydride, aniline, and glacial acetic acid is heated under reflux, the reaction mixture is cooled, the precipitated gray crystals are separated by filtration, treated with hydrochloric acid solution, then with hot sodium carbonate solution, and recrystallized from acetic acid. Acetyl derivative, the 4-acetylnaphthalic acid phenylimide is obtained.

[0017] At the second stage, the acetyl derivative, the 4-acetylnaphthalic acid phenylimide, is converted into an unsaturated ketone. To that end, 4-acetylnaphthalic acid phenylimide, ethanol, sodium hydroxide solution, and benzaldehyde are stirred at ambient temperature. The precipitate formed is separated by filtration, water washed till neutral reaction (litmus), dried, and re-crystallized from toluene. The product is obtained as yellow crystals.

[0018] At the third synthesis stage, the unsaturated ketone is treated with phenyl hydrazine in a mixture of ethanol and sodium hydroxide solution under reflux. The crystals precipitated from the mixture under cooling are separated by filtration, water washed till neutral reaction, and treated with boiling alcohol. The product obtained is purified using chromatography of toluene solution. The final product is obtained as red crystals at yield of 57 to 64%. The crystals are water-insoluble and soluble in organic solvents. Luminescence: in toluene, λ_(max)=570 nm.

[0019] The methods for preparing luminophors disclosed in the above-mentioned Author's Certificates are almost identical with each other except for that 4-acetylnaphthalic anhydride is treated with aniline to obtain orange-red luminophors (Ref.2) while to produce red ones, the same anhydride is reacted with o-phenylene diamine.

[0020] In this reaction, the same drawbacks are typical of both methods, namely:

[0021] (A) Low quality of the final product. The product contains considerable amounts of impurities, mainly unsaturated naphthalic acid derivatives that cause green fluorescence. The presence of such impurities in the final product is due to the preparation method itself. The final product purification from the impurities mentioned is associated with difficulties in the process, increased production costs, and substantial losses of the final product. To obtain high-quality luminophors, the chromatographic purification is required resulting in a loss of 30 to 40% of the final product. In Ref.2 the yields of various red range luminophors are said to be from 62 to 85%. The real useful product yield after the purification is, however, only from 35 to 50%.

[0022] (B) The process is difficult to perform and laborious. When producing orange, orange-red, and red luminophors, the corresponding intermediates, i.e., acetyl derivatives, are to be prepared every time. For example, 4-acetylnaphthalic anhydride is to be condensed with aniline preparing 4-acetylnaphthalic acid phenylimide to produce luminophors emitting in orange range, while to obtain red luminophors, the same anhydride must be condensed with o-phenylene diamine preparing 4(5)-acetyl-1,8-naphthoylene-1′,2′-benzimidazole. These preparations make the process difficult and increase its cost.

[0023] (C) Moreover, the process is complicated by the purification of intermediates both at the stages of their synthesis and at the preparation of final products.

[0024] Another method is known for preparing luminophors of the structure and emission region similar to the subject of this application; the method consists in that 4-cinnamoyl-1,8-naphthylene-1′,2′-benzimidazole is condensed with o-tolyl hydrazine in acetic acid medium under boiling, i.e., similar to the methods described above. The precipitate formed is separated by filtration, dried, and purified by the column chromatography. By this method, 4-[1-(2-methylphenyl)-5-phenyl-2-pyrazolinyl-3]-1,8-naphthoylene-1′,2′-benzimidazole with the structure shown is obtained.

[0025] The luminophore compounds so prepared are fluorescent in the orange-red spectral region with a large Stokes shift: intoluene, absorption at λ_(max)=470 nm, luminescence at λ_(max)=595 nm. (See Ref.3-USSR Author's Certificate No. 1,148,291, Cl. C09K 11/06).

[0026] The use of the method of the present invention will permit the synthesis of the named luminophores to be carried out faster with a higher yield of the product. That will eliminate the extra cost related to the use of chemicals and labor and will provide for the more economical synthesis of the product.

REFERENCES

[0027] 1. B. M. Krasovitskiy and E. A. Shevchenko “Method of preparation of organic luminophores”, USSR Authors Certificate (A.C.) #179324, c09d, B. I, 5 (1966).

[0028] 2. B. M. Krasovitskiy, E. G. Yushko, and D. G. Pereyaslova “Method of preparation of organic luminophores”, USSR Authors Certificate (A.C.) #196873, c09d, B. I, 2 (1967).

[0029] 3. V. M. Shershukov, B. M. Krasovitskiy and T. A. Shehovtsova “4-[1-(2-methylphenyl)-5-phenyl-2-pirazolynil-3]-1′,8′-naphthoylen-1′,2′-benzimidazole as an orange-red luminophore”, USSR Authors Certificate (A.C.) #1148291, c09k, 11/06, B. I, 47-48 (1993).

[0030] The USSR Authors Certificate is an equivalent of a patent that has been filed in the USSR only.

OBJECTS OF THE INVENTION

[0031] It is therefore an object of the present invention to develop a method for preparing pyrazolinylnaphthalic acid derivatives of the general formula

[0032] where

[0033] Ar₁ and Ar₂ are unsubstituted or substituted phenyl radicals bearing in the para position an alkylated or acylated oxy or amino group, or a polynuclear aryl radical; and

[0034] Ar₃ is a substituted N-naphthalimid or 1,8-naphthylene-1′,2′-benzimidazole.

[0035] It is another object of the present invention to provide a method to simplify and reduce the time it takes to synthesize the above compounds.

[0036] It is a further object of the present invention to enhance the final product yield and quality (purity grade) of the above compounds.

[0037] Additional objects and advantages of the invention are set forth, in part, in the description which follows and, in part, will be apparent to one of ordinary skill in the art from the description and/or from the practice of the invention.

SUMMARY OF THE INVENTION

[0038] In response to the foregoing challenge, Applicants have developed an innovative, economical method for preparing derivatives of the pyrazolinylnaphthalic acid having the general formula

[0039] where

[0040] Ar₁ and Ar₂ are unsubstituted or substituted phenyl radicals bearing in the para position an alkylated or acylated oxy- or amino group, or a polynuclear aryl radical; and

[0041] Ar₃ is a substituted N-naphthalimid or 1,8-naphthylene-1′,2′-benzimidazole.

[0042] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only, and are not restrictive of the invention as claimed. The accompanying drawings, which are incorporated herein by reference, and which constitute a part of this specification, illustrate certain embodiments of the invention, and together with the detailed description serve to explain the principles of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBOIDMENTS

[0043] Reference will now be made in detail to a preferred embodiment of the present invention, an example of which is illustrated in the accompanying examples.

[0044] The object of this invention is to develop a method for preparing pyrasolinylnaphthalic acid derivatives of general formula

[0045] where

[0046] Ar₁ and Ar₂ are unsubstituted or substituted phenyl radicals bearing an alkylated or acylated oxy- or amino group in the para position, or a polynuclear aryl radical; and

[0047] Ar₃ is a substituted N-naphthalimid or 1,8-naphthylene-1′,2′-benzimidazole.

[0048] The method ofthe present invention permits, by way of a novel change in the synthetic steps and conditions and simplification of the synthesis, reducing its labor requirements, and enhancing the final product yield and quality (purity grade).

[0049] This object is attained by the following. The previously known method includes the reaction of 4-acetylnaphthalic anhydride with organic reagents by way of a series of successive transformations resulting in formation of the corresponding ketone, treating of the latter with phenyl hydrazine or substituted phenyl hydrazine under heating in a solvent, and separation of the final product by filtration.

[0050] According to the present invention, the initial 4-acetylnaphthalic anhydride is first reacted with the corresponding aromatic or heterocyclic aldehyde in aqueous alkali medium, the formed disodium salt of cinnamoylnaphthalic acid is condensed with a substituted or unsubstituted aromatic amine obtaining the corresponding ketone and then with phenyl hydrazine, and the formed final product is separated.

[0051] The novel modification of the process and the modified stages and synthesis conditions, namely, reacting 4-acetylnaphthalic anhydride not with aromatic amine but with aromatic aldehyde makes it possible to exclude from the process the unsubstituted naphthalic acid comprised in the anhydride in considerable amounts as an impurity. Under the newly developed reaction mode, the unsubstituted acid does not interact chemically with the aromatic aldehyde (in contrast to the amine in the previously known method) and is removed from the reaction mixture as a solution of its sodium salt in the course of filtration of the formed disodium cinnamoyl naphthoate that is essentially insoluble in the aqueous alkali reaction medium.

[0052] In this reaction, a considerable amount of by-products are eliminated at the consecutive condensation of cinnamoylnaphhalic acid with aromatic amine. Moreover, the disodium cinamoyl naphthoate is the common intermediate in the synthesis of red range luminophors. For example, its interaction with aniline gives phenylimide of 4-cinnamoylnaphthalic acid while with o-phenylene diamine, 4(5)-cinnamoyl-1,8-naphthoylene-1′,2′-benzimidazole is obtained. This allows one to avoid the synthesis of specific intermediates for each color range, thus simplifying the process substantially.

[0053] The method of the present invention is realized according to the following scheme:

[0054] The process stages are as follows:

[0055] Treating 4-acetylnaphthalic anhydride with corresponding aldehyde in aqueous alkali medium to obtain disodium salt of 4-cinnamoylnaphthalic acid.

[0056] Treating the of 4-cinnamoylnaphthalic acid salt with corresponding mono- or diamine obtaining <<chalcone>>.

[0057] Interaction of the obtained <<chalcone>>with phenyl hydrazine or its substituted derivative in a solvent.

[0058] Separation of the formed final product from the reaction mixture by filtration.

[0059] Purification of the product by chromatography.

[0060] Some specific examples of the invention embodiments are presented below.

EXAMPLE 1 Preparation of 4-(1,5-diphenyl-2-pyrazolinyl)-N-phenyl naphthalimide

[0061] A mixture of4-acetylnaphthalic anhydride (10.8 g) (prepared by acenaphthene acylation with acetic anhydride in the presence of anhydrous zinc chloride with the consecutive oxidation of the formed acetyl acenaphthene with sodium dichromate), benzaldehyde (5.25 g), and 4.4% sodium hydroxide solution (120 ml) is stirred for 4 h at room temperature. The precipitate of disodium 4-cinnamoyl naphthoate is separated by filtration and washed with alcohol. A mixture of disodium 4-cinnamoyl naphthoate (15.79 g), aniline (4.89 g), and acetic acid (60 ml ) is boiled for 6 h. The reaction mixture is cooled down to room temperature (20° C.). The precipitate is separated by filtration and washed with water and hot alcohol. A mixture of 4-cinnamoyl-N-phenyl naphthalimide (12.1 g), phenyl hydrazine (4.26 g), ethanol (100 ml), and 10% alkali solution (6 ml) is boiled for 6 h, cooled down to 20° C., the precipitate is separated by filtration, washed with water and alcohol, and purified by chromatography on aluminum oxide eluting with chloroform/tetrachloromethane (1:1). The product is obtained as red crystals, m.p. 221-223° C., water-insoluble, soluble in usual organic solvents. Yield: 11.24 g (75%). Luminescence (toluene): λ_(max)=570 nm.

EXAMPLE 2 Preparation of 4-[(1-phenyl-5-(4-methoxyphenyl)-2-pyrazolinyl-3-]-N-phenyl naphthalimide

[0062] The compound is prepared and purified as described in Example 1. The initial products: 4-acetylnaphthalic anhydride (10.8 g), anisaldehyde (6.12 g), aniline (4.89 g), and phenyl hydrazine (4.1 g). The product is obtained as dark-red crystals, m.p. 215° C., insoluble in water, soluble in usual organic solvents. Yield: 12.13 g (80%). Luminescence (toluene): λ_(max)=575 nm.

EXAMPLE 3 Preparation of 4-[1,5-diphenyl-2-pyrazolinyl-3)]-N-(4-methoxyphenyl) naphthalimide

[0063] The compound is prepared and purified as described in Example 1. The initial products: 4-acetylnaphthalic anhydride (21.6 g), benzaldehyde (9.54 g), p-anizidine (13 g), and phenyl hydrazine (10.3 g). The final product yield is 83%. The product is obtained as red crystals, m.p. 268° C., insoluble in water, soluble inusual organic solvents. Luminescence (toluene): λ_(max)=570 nm.

EXAMPLE 4 Preparation of 4-[(2-naphthyl)-5-(4-methoxyphenyl)-2-pyrazolinyl-3-]-N-phenyl naphthalimide

[0064] The compound is prepared and purified as described in Example 1. The initial products: 4-acetylnaphthalic anhydride (10.8 g), anisaldehyde (6.12 g), aniline (4.89 g), and 2-naphthyl phenyl hydrazine (7.48 g). The product is obtained as dark-red crystals, m.p. 202-205° C., insoluble in water, soluble in usual organic solvents. Yield: 15.66 g (75%). Luminescence (toluene): λ_(max)=617 nm.

EXAMPLE 5 Preparation of 4-[(1-(4-carbomethoxyphenyl)-5-(4-methoxyphenyl-2-pyrazolinyl-3)]-N-phenyl naphthalimide

[0065] The compound is prepared and purified as described in Example 1. The initial products: 4-acetylnaphthalic anhydride (10.8 g), anisaldehyde (6.12 g), aniline (4.89 g), and 4-carbomethoxyphenyl hydrazine (7.86 g). The product is obtained as orange crystals, m.p.255-257° C., water-insoluble, soluble in usual organic solvents. Yield: 17.15 g (81%). Luminescence (toluene): λ_(max)=570 nm.

EXAMPLE 6 Preparation of 1,5-diphenyl-3-(1,8-naphthoylene-1′,2′-benzimidazolyl-4)-2-pyrazoline

[0066] The compound is prepared and purified as described in Example 1. The initial products: 4-acetylnaphthalic anhydride (10.8 g), benzaldehyde (5.25 g), o-phenylene diamine (5.68 g), and phenyl hydrazine (4.43 g). The product is obtained as red crystals, m.p. 262-263° C., insoluble in water, soluble in usual organic solvents. Luminescence (toluene): λ_(max)=598 nm.

EXAMPLE 7 Preparation of 1-phenyl-5-(4-methoxyphenyl)-3-(1,8-naphthoylene-1′,2′-benzimidazolyl-4)-2-pyrazoline

[0067] The compound is prepared and purified as described in Example 1. The initial products: 4-acetylnaphthalic anhydride (10.8 g), anisaldehyde (6.12 g), o-phenylene diamine (5.68 g), and phenyl hydrazine (4.6 g). The final product yield from 14.1 g of corresponding unsaturated ketone: 13.98 g (82%). The product is obtained as red crystals, m.p. 242-243° C., insoluble in water, soluble in usual organic solvents. Luminescence (toluene): λ_(max)=600 nm.

EXAMPLE 8 Preparation of 1-phenyl-5-furfurol-3-(1,8-naphthoylene-1′,2′-benzimidazolyl-4)-2-pyrazoline

[0068] The compound is prepared and purified as described in Example 1. The initial products: 4-acetylnaphthalic anhydride (10.8 g), furfurol (5.25 g), o-phenylene diamine (5.68 g), and phenyl hydrazine (4.4 g). The product is obtained as dark-brown crystals, m.p. 251-252° C., insoluble in water, soluble in usual organic solvents. Yield: 10.35 g (75%). Luminescence (toluene): λ_(max)=595 nm.

EXAMPLE 9 Preparation of 1-phenyl-5-(4-dimethylaminophenyl)-3-(1,8-naphthoylene-1′,2′-benzimidazolyl-4)-2-pyrazoline

[0069] The compound is prepared and purified as described in Example 1. The initial products: 4-acetylnaphthalic anhydride (10.8 g), 4-dimethylaminobenzaldehyde (5.25 g), o-phenylene diamine (5 g), and phenyl hydrazine (3.78 g). The final product yield from 11.95 g of corresponding unsaturated compound: 11.5 g (80%).The product is obtained as red crystals, m.p. 256-258° C., insoluble in water, soluble in usual organic solvents. Luminescence (toluene): λ_(max)=610 nm.

EXAMPLE 10 Preparation of 1-phenyl-5-(4-methoxyphenyl)-3- (1,8-naphthoylene-1′,2′-benzimidazolyl-4)-2-pyrazoline

[0070] The compound is prepared and purified as described in Example 1. The initial products: 4-acetylnaphthalic anhydride (10.8 g), anisaldehyde (6.12 g), o-naphthylene diamine (8.31 g), and phenyl hydrazine (4.54 g). The product is obtained as red crystals, m.p. 238-240° C., insoluble in water, soluble in usual organic solvents. Yield: 14.4 g (78%). Luminescence (toluene): λ_(max)=604 nm.

[0071] It is seen from the description and the examples that the method of the present invention develops a novel technologic method for preparing pyrazolinylnaphthalic acid being orange, orange-red, and red range luminophors. The method is simplified and more convenient as compared to known methods due to that, first, disodium salt of cinnamoylnapbthalic acid is a common intermediate in the synthesis of luminophors having all necessary emission colors, so there is no need for preparation of acetyl derivative specific for each color range and, second, there is no need for intermediates purification at each synthesis stage. This reduces considerably the production cost and labor consumption.

[0072] Due to the improvements mentioned above, the final product is essentially free of impurities, thus, its quality is improved. Since the losses at the intermediate process stages are reduced (due to the chromatographic purification is unnecessary), the yield of final pure products is enhanced up to 80% in contrast to 50% according to previously known methods. At present, the semi-industrial scale technology has been developed for preparing of products with various emission colors.

[0073] It will be apparent to those skilled in the art that various modifications and variations can be made in the construction, configuration, and/or operation of the present invention without departing from the scope or spirit of the invention. For example, in the embodiments mentioned above, various changes may be made to the synthesis or reagents without departing from the scope and spirit of the invention. Further, it may be appropriate to make additional modifications or changes to the reaction conditions without departing from the scope of the invention. Thus, it is intended that the present invention cover the modifications and variations ofthe invention provided they come within the scope of the appended claims and their equivalents.

METHOD FOR PRODUCING PYRAZOLINYLNAPHTALIC ACID DERIVATIVES

[0074] The proposed invention relates to a process for the production of pyrazolinylnaphtalic acid derivatives depicted by the following general formula:

[0075] [see original for figure]

[0076] where:

[0077] Ar₁ or Ar₂ is a substituted phenyl radical that contains an alkylated or acylated oxy- or amine group in a n-position or a polynuclear aromatic radical;

[0078] Ar₃ is a substituted N-naphtalimide or 1,8-naphtoilene-1′,2′-benzimidazole.

[0079] Compounds with the above general formula are high-efficiency organic luminophors with orange, orange-red and red emission colors and are widely used in various fields of science and technology. Apart from being used as fluorescent compound dyes for plastics and liquid scintillators, they are also utilized in hydrogeology (in water flow studies), for marking effluents from chemical plants, as lasing media and for other purposes.

[0080] There is a known method for producing pyrazolinylnaphtalic acid derivatives which are depicted by the following general formula:

[0081] [see original for figure]

[0082] where: R₁ is an unsubstituted or substituted aromatic or heterocyclic radical;

[0083] R₂ is an unsubstituted or substituted aromatic radical;

[0084] R₃ is alkyl, aryl, alkoxygroup, halides.

[0085] Compounds depicted by the above general formula are organic luminophors with orange-red and red emission colors.

[0086] The above compounds are made from the products of condensation of a 4-acetylnaphtalic anhydride with an unsubstituted or substituted o-phenyldiamine in glacial acetic acid. The reaction results in the formation of yellowish-green crystals which are separated by filtering and recrystallized with the use of acetic acid. The formed acetyl derivative of 1,8-naphtoilene-1′-2′-benzimidazole is caused to react with aromatic or heterocyclic aldehyde in a mixture of ethyl alcohol and caustic soda, stirred at room temperature and diluted with water. The formed precipitate is separated by filtering and recrystallized with the use of acetic acid. Unsaturated ketone is obtained. This unsaturated ketone is then treated with phenylhydrazine or its substitute in glacial acetic acid while boiling, then the solution is allowed to cool down and the formed crystals are separated by filtering, washed with methanol on the filter, and allowed to dry. The formed product consists of red or dark red crystals which are soluble in common organic solvents and are water-insoluble. End commercial product yield from 62 to 85% _(max. lum.)in toluene from 598 to 610 nm _(max. lum.)in crystals from 620 to 670 nm (see USSR Author's Certificate No. 179324, CO7d) There is another method for producing luminophors- pyrazolinylnaphtalic acid derivatives-with the following general formula:

[0087] [see original for figure]

[0088] where:

[0089] R₁ and R₂ are unsubstituted or substituted aromatic radicals. Compounds with the above structure are organic luminophors with orange, orange-red and red emission colors.

[0090] The method for their production consists in that in the first synthesis step a mixture of 4-acetylnaphalic anhydride, aniline and glacial acetic acid is boiled, then the reaction mixture is allowed to cool down, and the formed gray crystals are separated by filtering, treated with hydrochloric acid solution and hot soda solution and recrystallized with the use of acetic acid. Acetyl derivative—phenylimide-4-acetylnaphtalic acid—is consequently formed.

[0091] In the second step, phenylimide-4-acetylnaphtalic acid is transformed to unsaturated ketone. To this end, phenylimide-4-acetylnaphtalic acid, ethyl alcohol, caustic soda solution and benzaldehyde are mixed together at room temperature. The formed precipitate is separated by filtering, washed with water until litmus paper shows a neutral reaction, allowed to dry and recrystallized with the use of toluene.

[0092] Yellow crystals are thus obtained.

[0093] In the third synthesis step, the formed unsaturated ketone is treated with phenylhydrazine while boiling in a mixture of ethyl alcohol and caustic soda solution. Crystals that precipitate as a result of the cooling of the solution are separated by filtering, washed with water until litmus paper shows a neutral reaction, and treated with alcohol while boiling.

[0094] The formed product is chromatographically cleaned with the use of toluene solution.

[0095] The end product is made up of red crystals. Its yield ranges from 57 to 64%.

[0096] Crystals are soluble in organic solvents and water-insoluble. _(max. lum.) in toluene is 570 nm (see USSR Author's Certificate No. 196873, C07d).

[0097] The production methods described in the above Author's Certificates are similar except that in order to produce luminophors with orange-red emission colors 4-acetylnaphtalic anhydride is treated with aniline (Author's Certificate No. 196873) and to obtain luminophors with red emission colors 4-acetylnaphtalic anhydride is caused to react with o-phenyldiamine.

[0098] The above two methods have the same shortcomings, viz.:

[0099] A) Low quality of the end product.

[0100] The end product has a high proportion of impurities which mainly consist of unsaturated naphtalic acid and which provide for green luminescence. The presence of such impurities in the end product is caused by the method of its preparation, since when the prototype production process is used the end product of 4-acetylnaphtalic acid is not freed from unsaturated naphtalic acid, which is an associate of the commercial product.

[0101] The removal of such impurities from the product presents technological difficulties, and it is associated with material costs and a considerable loss of the end product.

[0102] To obtain high-quality luminophors, the chromatographic cleaning of the product is needed with the resulting loss of 30 to 40% of the end product.

[0103] According to the above Author's Certificates, the yields of the end products with different color ranges of red hues vary from 62 to 85%. However, the actual yield of the product suitable for use after cleaning is about 35 to 50%.

[0104] B) Complexity and Labor Intensiveness of Process

[0105] In producing luminophors of orange, orange-red and red emission colors, each time it is necessary to obtain the corresponding intermediate products, i.e.; the corresponding acetyl derivatives. Thus, to produce luminophors of orange emission colors, 4-acetylnaphtalic anhydride is condensed with aniline with the formation of phenylimide-4-acetylnaphtalic acid, and to produce luminophors of red emission colors, 4-acetylnaphtalic anhydride is condensed with o-phenylenediamine with the formation of 4(5)-acetyl-1,8-naphtoilene-1′,2′-benzimidazole, which complicates the process and makes it more expensive.

[0106] Besides, the process is complicated by need for cleaning the intermediate products both when they are synthesized and when the end product is formed.

[0107] A method for producing luminophors similar in structure and emission range to luminophors produced by the proposed method is known, which like the above method consists in the condensation of 4-cinnamoine-1,8-naphtoilene-1′,2′-benzimidazole with o-tolylhydrazine in acetic acid while boiling. The formed precipitate is separated by filtering, allowed to dry and chromatographically cleaned. The end product is 4-[1-(2-methylphenyl)-5-phenyl-2-pyrosolinyl-3]-1,8-naphtoilene-1′,2′-benzimidazole depicted by the following formula:

[0108] [see original for figure]

[0109] The produced compounds fluoresce in the orange-red spectral region and are characterized by a large Stokes shift.

[0110]_(max. abs.) in toluene—470 rm.

[0111]_(max. lum.) in toluene—595 nm.

[0112] (see USSR Author's Certificate No. 1148291, C09K1 1/06, C07 231/06).

[0113] As a prototype, use is made of the method described in Author's Certificate No. 179324 since this method is protected to a greater extent and has not yet lost its topicality.

[0114] The goal of the invention was to develop such a method for producing pyrazolinylnaphtalic acid derivatives with the above formula which would make it possible to considerably simplify the process, reduce its labor intensiveness, and increase the end product yield and quality (purity) by changing the sequence of production operations and the conditions under which they are performed.

[0115] This goal is achieved as follows: as distinct from the known method (which includes the interaction between 4-acetylnaphtalic anhydride and organic reagents through a number of consecutive transformations with the formation of the corresponding ketone, its treatment with phenylhydrazine or with phenylhydrazine substitute while being heated in a solvent and the separation of the reaction product by its filtering), the source 4-acetylnaphtalic anhydride is at first caused to react with the corresponding aromatic or heterocyclic aldehyde in a water-alkali mixture and the produced disodium salt of cinnamoylnaphtalic acid is condensed with substituted or unsubstituted aromatic amine with the formation of the corresponding ketone, whereupon it is treated with phenylhydrazine the same way as when the prototype method is used with the formation of the end product.

[0116] The use of the process with another sequence of production steps and different synthesis conditions, i.e. with 4-acetylnaphtalic anhydride interacting not with aromatic amine (as when the prototype method is used), but with aromatic aldehyde makes it possible to get rid of naphtalic acid impurities which are present in considerable quantities in this anhydride. Under the reaction conditions there is no chemical interaction between this acid and aromatic aldehyde (as distinct from amine when the prototype method is used) and the acid is removed from the reaction mixture in the form of its sodium salt solution as a result of filtering the formed disodium salt of cinnamoylnaphtalic acid, which is practically insoluble in the reaction mixture of water and alkali. Owing to this, a high proportion of side products is removed during the subsequent condensation of cinnamoylnaphtalic acid. Besides, the produced disodium salt of cinnamoylnaphtalic acid is a common intermediate product needed for producing luminophors of the red emission range.

[0117] Thus, the interaction with aniline results in the production of phenylimide-4-cinnamoylnaphtalic acid, and the interaction with o-phenyldiamine results in the production of 4(5)dinamoyl-1,8-naphtoilene-1′,2′-benzimidazole. This makes it possible not to obtain the intermediate product for each color range, which contributes to a considerable improvement of the process.

[0118] The proposed method can be described diagrammatically as follows:

[0119] [see original for figure]

[0120] Treatment of 4-acetylnaphtalic anhydride with the corresponding aldehyde in a water-alkali mixture with the formation of disodium salt of 4-cinnamoylnaphtalic acid.

[0121] Treatment of disodium salt of 4-cinnamoylnaphtalic acid with the corresponding amine (monoamine or diamine) with the formation of chalcone.

[0122] Interaction between the corresponding formed chalcone and phenylhydrazine or its substitute in a solvent.

[0123] Separation of the end product from the reaction mixture by filtering.

[0124] Chromatographic cleaning of the end product.

[0125] Specific Examples of Using Proposed Method

EXAMPLE 1 Production of 4-(1,5-diphenyl-2-pyrasolinyl-3)-N-phenylnaphtalimide

[0126] A mixture of 10.8 g of 4-acetylnaphtalic anhydride (obtained by the acetylation of acenaphtene with acetic anhydride in the presence of anhydrous zinc chloride and by the oxidation of the formed acetylnaphtene with sodium dichromate), 5.3 g of benzaldehyde, and 120 ml of 4.4% caustic soda solution is stirred at room temperature for 3 hours. The precipitate—disodium salt of 4-cinnamoylnaphtalic acid—is separated by filtering and washed with alcohol.

[0127] A mixture of 15.79 g of disodium salt of 4-cinnamoylnaphtalic acid, 4.89 g of aniline and 60 ml of acetic acid is boiled for 6 hours. The reaction mixture is then allowed to cool down to room temperature (20° C.). The formed precipitate is separated by filtering and washed on the filter with water and hot alcohol.

[0128] A mixture of 12.1 g of 4-cinnamoyl-N-naphtalimide, 4.26 g of phenylhydrazine, 100 ml of ethyl alcohol and 6 ml of 10% alkaline solution is boiled for 6 hours and allowed to cool down to 20° C. The formed precipitate is separated by filtering and washed with water and then with alcohol. The end product is made up of red crystals, its melting temperature is 221 to 223° C., and it is soluble in common organic solvents and water-insoluble. The yield is 11.24 g (75%).

[0129]_(max lum.) in toluene is 570 nm.

EXAMPLE 2 Production of 4-[1-phenyl-5-(4-methoxyphenyl)-2-pyrazolinyl-3)-N-phenylnaphtalimide

[0130] This compound is produced and cleaned as the product in example 1. The source products are 4-acetylnaphalic anhydride (10.8 g), anisic aldehyde (6.12 g), aniline (4.89 g), and phenylhydrazine (4.1 g).

[0131] The end product is made up of dark red crystals; it is soluble in common organic solvents and water-insoluble. The melting temperature is 215° C. The yield is 12.13 g (80%).

[0132]_(max. lum.) in toluene is 575 nm.

EXAMPLE 3 Production of 4-[1,5-diphenyl-2-pyrazolinyl-3)-N-(4-methoxyphenyl)]-naphtalimide

[0133] This compound is produced and cleaned as the product in example 1. The source products are 4-acetylnaphalic anhydride (21.6 g), benzaldehyde (9.54 g), n-anisidine (13 g), and phenylhydrazine (10.3 g).

[0134] The end product yield from 31.54 g of the corresponding unsaturated ketone is 31.6 g (83%).

[0135] The formed red crystals have a melting temperature of 268° C.; they are soluble in common organic solvents and water-insoluble.

[0136]_(max lum.) in toluene is 570 nm.

EXAMPLE 4 Production of 4-[1-(2-naphtyl)5-(4-methoxyphenyl)-2-pyrazolinyl-3)-N-phenylnaphtalimide

[0137] This compound is produced and cleaned as the product in example 1. The source products are 4-acetylnaphalic anhydride (10.8 g), anisic aldehyde (6.12 g), aniline (4.89 g), and 2-naphtylhydrazine (7.48 g).

[0138] The end product is in the form of dark red crystals with a melting temperature of 202 to 205° C. They are soluble in common organic solvents and water-insoluble. The yield is 15.65 g (75%).

[0139]_(max. lum.) in toluene is 617 nm.

EXAMPLE 5 Production of 4-[1-(4-carbomethoxyphenyl)-5-(4-methoxyphenyl-2-pyrazolinyl-3)]-N-phenylnaphtalimide

[0140] This compound is produced and cleaned as the product in example 1. The source products are 4-acetylnaphalic anhydride (10.8 g), anisic aldehyde (6.12 g), aniline (4.89 g), and 4-carbomethoxyphenylhydrazine (7.86 g). The end product is made up of orange crystals with a melting temperature of 255 to 257° C.; they are soluble in common organic solvents and water-insoluble. The yield is 17.15 g (81%).

[0141]_(max. lum.) in toluene is 570 nm.

EXAMPLE 6 Production of 1,5-diphenyl-3-[1,8-naphtoilene-1′,2′-benzimidazolyl-4)-2-pyrazolene

[0142] This compound is produced and cleaned as the product in example 1. The source products are 4-acetylnaphalic anhydride (10.8 g), benzaldehyde (5.25 g), o-phenylenediamine (5.68 g), and phenylhydrazine (4.43 g). The end product is made up of red crystals with a melting temperature of 262 to 263° C.; they are soluble in common organic solvents and water-insoluble. The yield is 12.22 g (79%).

[0143]_(max. lum.) in toluene is 598 nm.

EXAMPLE 7 Production of 1-phenyl-5-[4-methoxyphenyl)-3-[1,8-naphtoilene-1′,2′-benzimidazolyl-4)]-2-pyrazolene

[0144] This compound is produced and cleaned as the product in example 1. The source products are 4-acetylnaphalic anhydride (10.8 g), anisic aldehyde (6.12 g), o-phenylenediamine (5.68 g), and phenylhydrazine (4.6 g).

[0145] The end product is made up of red crystals with a melting temperature of 242 to 243° C.; they are soluble in common organic solvents and water-insoluble. The yield from 14.1 g of the corresponding unsaturated ketone is 13.98 g (82%).

[0146]_(max. lum.) in toluene is 600 nm.

EXAMPLE 8 Production of 1-phenyl-5-furfurol-3-(1,8-naphtoilene-1′,2′-benzimidazolyl-4)-2-pyrazolene

[0147] This compound is produced and cleaned as the product in example 1. The source products are 4-acetylnaphalic anhydride (10.8 g), furfurol (4.78 g), o-phenylenediamine (5.18 g), and phenylhydrazine (4.04 g). The end product is made up of dark red crystals with a melting temperature of 251 to 252° C.; they are soluble in common organic solvents and water-insoluble. The yield is 10.35 g (75%).

[0148]_(max. lum.) in toluene is 595 nm.

EXAMPLE 9 Production of 1-phenyl-5-(4-dimethylaminophenyl)-3-[(1,8-naphtoilene-1′,2′-benzimidazolyl-4)]-2-pyrazolene

[0149] This compound is produced and cleaned as the product in example 1. The source products are 4-acetylnaphalic anhydride (10.8 g), 4-dimethylaminobenzaldehyde (7.37 g), o-phenylenediamine (5 g), and phenylhydrazine (3.78 g).

[0150] The end product is made up of red crystals with a melting temperature of 256 to 258° C.; they are soluble in common organic solvents and water-insoluble. The yield from 11.95 g of the corresponding unsaturated compound is 11.5 g (80%). _(max. lum.) in toluene is 610 nm.

EXAMPLE 10 Production of 1-phenyl-5-(4-methoxyphenyl)-3-(1,8-naphtoilene-1′,2′-naphtimidazolyl-4)-2-pyrazolene

[0151] This compound is produced and cleaned as the product in example 1. The source products are 4-acetylnaphalic anhydride (10.8 g), anisic aldehyde (6.12 g), o-naphtilenediamine (8.31 g), and phenylhydrazine (4.54 g).

[0152] The end product is made up of dark red crystals with a melting temperature of 238 to 240° C.; they are soluble in common organic solvents and water-insoluble. The yield is 14.4 g (78%), and _(max. lum.) in toluene is 604 nm.

[0153] As can be seen from the description of the proposed method and the examples of its use, the proposed sequence of operations and the conditions created for their performance made it possible to develop a process for producing of pyrazolinylnaphtalic acid derivatives (luminophors of the orange, orange-red and red color ranges), which is simpler and more adaptable to production conditions than the prototype, due to the fact that firstly, disodium salt of cinnamoylnaphtalic acid is a common intermediate product for synthesizing luminophors of the requisite color and there is no need to obtain acetyl derivatives for each color range, and secondly, there is no need to free the mixture from intermediate product impurities during the synthesis. This made it possible to considerably reduce the material costs and the labor input.

[0154] Due to the above improvement of the process, the end product is practically free of impurities with the result that is has a higher quality.

[0155] Owing to the reduction in the losses during the formation of intermediate products (no cleaning is required), the yield of the pure end product (which is 50% in the case of the prototype method) is as high as 80%.

[0156] So far, a semi-industrial process for obtaining the needed products of various color ranges has been developed. 

We claim:
 1. A method for preparing pyrazolinylnaphthalic acid derivatives of the general formula

wherein Ar₁ and Ar₂ are selected from the group consisting of unsubstituted or substituted phenyl radicals bearing in the para position substituents selected from the group consisting of an alkylated or acylated oxy or amino group, or a polynuclear aryl radical; and wherein Ar₃ is selected from the group consisting of a substituted N-naphthalimid or 1,8-naphthylene-1′,2′-benzimidazole, said method comprising the steps of: reacting 4-acetylnaphthalic anhydride with organic reagents through a series of successive transformations resulting in formation of a corresponding ketone; treating of said ketone with a chemical selected from the group consisting of phenyl hydrazine or substituted phenyl hydrazine under heating in a solvent; and separation of the final product by filtration; wherein said 4-acetylnaphthalic anhydride is reacted with the corresponding compound selected from the group consisting of aromatic or heterocyclic aldehyde in aqueous alkali medium; and the formed disodium salt of cinnamoylnaphthalic acid is condensed with an aromatic amine selected from the group consisting of a substituted or unsubstituted aromatic amine obtaining said ketone. 